Numerous systems for monitoring glucose amount or concentration in a subject are known in the art, including, but not limited to the following: U.S. Pat. Nos. 5,362,307, 5,279,543, 5,695,623; 5,713,353; 5,730,714; 5,791,344; 5,840,020; 5,995,860; 6,026,314; 6,044,285; 6,113,537; 6,188,648, 6,326,160, 6,309,351, 6,299,578, 6,298,254, 6,284,126, 6,272,364, 6,233,471, 6,201,979, 6,180,416, 6,144,869, 6,141,573, 6,139,718, 6,023,629, 5,989,409, 5,954,685, 5,827,183, 5,771,890, and 5,735,273.
Self-monitoring of blood glucose (BG) is a critical part of managing diabetes. However, most procedures for obtaining such information are invasive, painful and provide only periodic measurements. Results from the Diabetes Control and Complication Trial Research Group, (The Diabetes Control and Complication Trial Research Group. N Engl J Med. 1993;329:997–1036), UK Prospective Diabetes Study (UK Prospective Diabetes Study (UKPDS) Group. Lancet. 1998;352:837–853), and Kumamoto trials (Ohkubo Y, Kishikawa H, Araki E, et al. Diabetes Res Clin Pract. 1995;28:103–117) showed that a tight glucose control regiment, which uses frequent glucose measurements to guide the administration of insulin or oral hypoglycemic agents, leads to a substantial decrease in the long-term complications of diabetes; however, there was a 3-fold increase in hypoglycemic events (The Diabetes Control and Complication Trial Research Group. N Engl J Med. 1993;329:997–1036.). Moreover, as many as 7 BG measurements per day were not sufficient to detect a number of severe hypoglycemic and hypoglycemic events (Ohkubo Y, Kishikawa H, Araki E, et al. Diabetes Res Clin Pract. 1995;28:103–117.).
The commercially available GlucoWatch® (Cygnus Inc., Redwood City, Calif.) biographers (Tamada, et al., JAMA 282:1839–1844, 1999) provide a means to obtain painless, automatic, frequent and noninvasive glucose measurements (see, for example, U.S. Pat. Nos. 6,326,160, 6,309,351, 6,299,578, 6,298,254, 6,284,126, 6,272,364, 6,233,471, 6,201,979, 6,180,416, 6,144,869, 6,141,573, 6,139,718, 6,023,629, 5,989,409, 5,954,685, 5,827,183, 5,771,890, and 5,735,273). The first generation device provides up to 3 readings per hour for as long as 12 hours after a single BG measurement for calibration (Tamada, et al., JAMA 282:1839–1844, 1999). The second generation device, the GlucoWatch® G2™ (Cygnus Inc., Redwood City, Calif.) biographer, provides up to six readings per hour for as long as 13 hours after a single BG measurement for calibration. The devices provide detailed information on glucose patterns and trends. The devices use an electrode produced by thick film deposition of an ink material.
The ink material usually consists of platinum black and/or platinum-on-carbon as the catalyst, graphite as a conducting material, a polymer binding material, and an organic solvent. U.S. Pat. No. 6,042,751 to Chan and Kuty pertains to a conductor composition of up to 5% platinum powders and/or platinum deposited on graphite, modified graphite and a thermoplastic polymer such as the styrene-containing acrylic copolymers poly(styrene-acrylonitrile). U.S. Pat. No. 6,309,535 to Williams et al. pertains to an electrode consisting of graphite particles coated with a transition metal catalyst, carbon particles, and a binder that is a vinyl chloride/vinyl acetate copolymer.
U.S. Pat. No. 5,928,571 to Chan discloses a conductive composition for iontophoretic electrodes containing silver particles, silver chloride particles, carbon and graphite as the conducting material, and a copolymer of hydrophilic and hydrophobic monomers. The hydrophobic monomers can be styrene, and the hydrophilic monomers can be acrylates.
The above-described compositions have several disadvantages, for example, they have a high cost of manufacture, and/or they are difficult to manufacture.
The present invention provides methods and compositions for improving performance of analyte monitoring systems that employ sensing electrodes, for example, the GlucoWatch biographer.